In oil-lubricated gearboxes, a ventilation opening is provided which, as the temperature rises and falls in operation of the gearbox, allows a pressure balance with the environment and is usually designed as a device with fittings to retain oil mist and exclude dirt from the environment.
WO 2007/098523 A1 discloses a water-containing lubricant which as well as a high proportion of water contains a medium for lowering the freezing point, for example glycol, and further additives or suspended matter. Further details of this and the benefits which can be achieved with such a lubricant are given in the publication.
German Patent Publication DE 22 20 565 discloses a recirculating cooling system for oil-lubricated reducing gears. A fan recirculates air containing oil vapour from the interior of the gearbox through a heat exchanger and back to the gearbox. The condensed oil is returned separately. There is no pressure balance with the environment.
WO 2010/037829 A1 discloses a ventilation device for gearboxes with water-containing lubricant. The ventilation device is connected with the gearbox via a line. The device has a condenser in which inflowing water vapour can condense so that the condensate drains back into the gearbox via the same line.
All of the aforementioned condensation devices are designed to condense vapour from gearbox lubricants. To lubricate combustion engines or to lubricate and cool electric motors, normally oil is used. When a fluid lubricant containing water is used in internal combustion engines or also in electric motors, because of the high thermal load and temperatures significantly higher than 100° Celsius, a massive evaporation of the water component occurs, and hence, a continuous reduction in and change in the composition of the lubricant and coolant. In contrast to gearboxes, the rapid and high temperature input from components such as the cylinders of an internal combustion engine or the windings in an electric motor evaporates the water component of the lubricant immediately, leading to great expansion of the water and the formation of water vapour. This greatly increased expansion causes a rise in the flow speed in the ventilation system, and a condensation device as described in WO 2010/037829 can no longer condense adequately.